BACKGROUND: To report usability, safety, and efficacy of the self-centering Solysafe Septal Occluder for transcatheter closure of secundum type atrial septal defect (ASD) in paediatric patients.METHODS: Retrospective observational clinical study in two tertiary care centers for congenital heart diseases.PATIENTS: First 37 (median age 8.7 years, 68% female) consecutive patients with an ASD stretched diameter up to 22 mm in whom a Solysafe Septal Occluder was used to close a haemodynamically significant ASD.INTERVENTIONS: Transcatheter closure of ASD was performed under general anaesthesia with trans-esophageal echo guidance. Stretched diameter of the ASD was assessed by balloon sizing.MAIN OUTCOME MEASURES: Rate of success, complete closure rate, and complications (defined as vascular complications, device-related complications such as embolism, thrombus formation, device erosions, infections, and arrhythmia) during follow up.RESULTS: 37 procedures were performed, success rate was 87% (32 of 37 pts.). A missing retroaortic rim was the main reason for device failure. Complete ASD closure rate was 78% immediately in cath lab (25 of 32 pts.), 90% after four weeks (28 of 31 pts.), 94% after three months (29 of 31 pts.), and 100% after six months (20 of 20 pts.). Procedure-related complication was femoral vein thrombosis in one patient.CONCLUSIONS: The Solysafe Septal Occluder is a feasible, safe, and clinically efficient new device for interventional closure of small to medium sized ASDs less than 23 mm stretched diameter in childhood. Limitations for the Solysafe device are ASDs with absent retroaortic rims and very small children with a body weight<10 kg.